Sorry folks, I found there is only S/MIME support in eM Client for SHA1 and MD5 for signatures and 3DES, RC2 and DES for encryption. In also needs SHA256, SHA384 and SHA512 for signatures and most importantly AES for encryption added to the algorithm suite. I need AES to keep things from breaking.
I guess this is a feature request Mark. Had you posted it as an Idea, I would certainly have given you my vote.